Each day a different image or photograph is featured, with an
accompanying caption, which deals with various topics in Earth Science.

End of the Rainbow

The above untouched photo shows a gorgeous rainbow taken on the first day of autumn (2002) at North Cape, Norway. Late in the afternoon, approximately 4:00 pm, just the right geometry of a low hanging Sun and rain showers bursting from ripe cumulus clouds produced this beautiful bow, not far from the northernmost point of continental Europe. Large water drops, greater than 1 mm in diameter, result in the most vibrant colors. The rain drops in the clouds pictured above were evidently at least this large - each spectral color can be readily identified. Since it's late afternoon, we know that the camera is facing east - rainbows only form opposite the Sun. In addition, since the bow is high in the sky, we know that the Sun was relatively near the horizon. Note that the area inside the bow is markedly lighter than the area outside of it. Rays of sunlight that strike near the center of rain drops are responsible for this phenomenon. These rays are scattered in such a way to redistribute sunlight so that the sky is brightened on the inside of the primary rainbow.

The cliffs of North Cape (standing about 307 m or nearly 1,000 ft in height) loom over the sea and provide a nice backdrop to the rainbow. A radar observation tower can be seen on top of the cliffs. There seems to be a ripple in the water close to where the bow dips into the sea. It's an illusion, but a nice touch nevertheless. To capture the photo, a Reflex Camera with an 80 mm lens was used.